Oxygen tank key



FIG. 1 is a front elevational view of an “oxygen tank key” showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a right side elevational view thereof, the left side being identical thereto; and,

FIG. 6 is a perspective view thereof.

The broken lines in FIG. 4, which define the bounds of the claimed design, form no part thereof. 

The ornamental design for an “oxygen tank key,” as shown and described. 